Kerenskaya G, Schnupf U, Basinger WH, Heaven MC. Spectroscopic and theoretical characterization of the AΔ2-XΠ2 transition of CH–Ne.
J Chem Phys 2005;
123:054304. [PMID:
16108636 DOI:
10.1063/1.1946747]
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Abstract
The A2delta-X2pi transition of CH-Ne was examined using laser-induced fluorescence and fluorescence depletion techniques. The spectrum was found to be particularly congested due to the large number of bound states derived from the CH(A,n=2)+Ne interaction, and the small energy spacings between these states resulting from the relatively weak anisotropy of the van der Waals bond. High-level ab initio calculations were used to generate two-dimensional potential energy surfaces for CH(X)-Ne and CH(A)-Ne. The equilibrium structures from these surfaces were bent and linear for the X and A states, respectively. Variational calculations were used to predict the bound states supported by the ab initio surfaces. Empirical modification of the potential energy surfaces for the A state was used to obtain energy-level predictions that were in good agreement with the experimental results. Transitions to all of the optically accessible internal rotor states of CH(A,n=2)-Ne were identified, indicating that CH performs hindered internal rotations in the lowest-energy levels of the A and X states. The characteristics of the potential energy surfaces for CH-Ne in the X,A,B, and C states suggest that dispersion and exchange repulsion forces dominate the van der Waals interaction.
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